Radioactive method enables determination of surface areas rapidly and accurately

Radioactive krypton adsorption technique is used to determine the surface area of more than one sample of material simultaneously

Physicochemical and bacteriological quality of water collected from dams and rivers along gold mining sites in Zamfara State

The physicochemical properties of water such as pH, temperature, conductivity, total dissolved solids, total suspended solid, alkalinity, dissolved oxygen, chloride, turbidity, hardness, sulphate, chemical oxygen demand and biochemical oxygen of the three major dams and rivers in Zamfara State were analyzed using standard analytical methods. The influence of seasonal variability on the parameters was also considered. Bacteriological assessment was also conducted to determine the bacteria load of the water bodies. The total bacterial counts obtained during the wet season (3.6 x 106 to 8.9 x 106) were generally higher than those obtained in the dry (2.4 x105 to 7.9 x 105). The microbial values recorded in the dam which ranged from (2.4 x105 to 7.4 x 106) and rivers (5.2 x105 to 8.9 x 106) water body represent high bacteria load compared to the recommended standards for drinking water (WHO, 2008; EPA, 2010; USEPA, 2002). The result of the physicochemical parameters revealed marked variations and non-uniform distribution from one season to another for two years of study. The results further showed that pH, temperature, EC, TDS, TSS, alkalinity, DO, BOD, COD, Cl, and SO4 have values that fall below the USEPA standard limit for drinking water with exception of turbidity (88.67 mg/l) that has a value higher than the recommended standard limit. Analysis of variance on the data collected revealed that there were significant difference (P < 0.05) between the parameters based on locations and seasons. Multiple range test conducted on the parameters also showed a significant difference between the wet and dry seasons. A combined mean of the parameters further revealed a significant different between the years

A Framework for Sustainable Maintenance of Offshore Energy Structures

This paper proposes a structure for maintenance decision support suitable for application to renewable energy assets. The method combines subjective tacit knowledge of subject-area experts with well-structured Analytical Hierarchical Process (AHP) to elicit weights of criteria relevant for effects evaluation of possible failures modes towards support for component’s maintenance decisions. The Technique for Ordered Preference using Similarity to Ideal Solution (TOPSIS) algorithm is adopted for aggregating the evaluation scores and achieving priority indexing given the conflicting characteristics of some criteria. Part of the highlights of the Framework is the implementation of the group experts, as well as individual expert's elicitations in a complimentary manner that eliminates subjective opinions and achieves a repeatable evaluation score. The conclusion of the analysis is the prioritisation of the component’s failure; An indicative case study of offshore wind turbine jacket support structure is used to demonstrate the applicability of the approach and the analysis results-which shows priority failure modes for focused maintenance intervention as bending of Chord/Brace ( ), collapse of Chord/Brace ( ), buckling of Long piles ( ), and Truss( ), overturning of Skirt pile ( ), and fatigue of Long pile ( ), further demonstrates the capacity of the model to support maintenance decisions. Caution is exercised in the selection of criteria that would capture the objectives of the risk analyses by consulting wide range of industry experts. Keywords— AHP, Expert, Offshore energy, TOPSIS, Wind turbine Support Structur

Anatomic Site Variability in Rat Skeletal Uptake and Desorption Of Fluorescently Labeled Bisphosphonate

Objectives Bisphosphonates commonly used to treat osteoporosis, Paget’s disease, multiple myeloma, hypercalcemia of malignancy and osteolytic lesions of cancer metastasis have been associated with bisphosphonate-associated jaw osteonecrosis (BJON). The underlying pathogenesis of BJON is unclear, but disproportionate bisphosphonate concentration in the jaw has been proposed as one potential etiological factor. This study tested the hypothesis that skeletal biodistribution of intravenous bisphosphonate is anatomic site-dependent in a rat model system. Materials and Methods Fluorescently labeled pamidronate was injected intravenously in athymic rats of equal weights followed by in vivo whole body fluorimetry, ex vivo optical imaging of oral, axial and appendicular bones and ethylenediaminetetraacetic acid bone decalcification to assess hydroxyapatite-bound bisphosphonate. Results Bisphosphonate uptake and bisphosphonate released per unit calcium were similar in oral and appendicular bones but lower than those in axial bones. Hydroxyapatite-bound bisphosphonate liberated by sequential acid decalcification was highest in oral relative to axial and appendicular bones (p \u3c 0.05). Conclusions This study demonstrates regional differences in uptake and release of bisphosphonate from oral, axial and appendicular bones of immune deficient rats

Combating Greenhouse Effects through Biomass Gasification: A Focus on Kinetic Modeling of Combustion and Gasification Zones

The prevalent challenges of global warming, food security, food production, crop production systems, environment control called for consideration and better utilization of green energy system such as biomass. The advanced thermo-chemical conversion of the renewable energy source which is aimed at production of optimal yield of energy has not been well understood. In order to have better physical insights into the detailed structure of the biomass burning process inside a solid bed, the kinetics of the biomass combustion and gasification must be properly analyzed. Consequently, improved kinetic models of the combustion and gasification zones in the thermochemical conversion system are very required. Therefore, the present study focuses on the development of improved kinetic modeling of the combustion and gasification zones in the biomass gasification system. The performance of the biomass gasifier system is evaluated through the equivalence ratio, the syngas composition, cold gas efficiency and lower heating value. Also, the effects of the equivalent ratio on gas compositions, the gasifier performance and the low heating value of the biomass are analyzed. From the analysis, it is established that the concentration of CO, H2 and CH4 in the gasifier decrease as the equivalence ratio increases. However, CO2 concentration increases with an increase in the equivalence ratio. The cold efficiency and LHV decreases as the equivalence ratio increases while the gas yield increases with an increase in the equivalence ratio. The quantity of gas produced increases as the amount of oxygen consumed increases. Also, the ratio of CO/CO2 decreases as the temperature of the reduction zone increases. Such analysis as presented in this work, is very useful as a time-saving and cost-effective tool for designing and optimizing the biomass gasifier. Therefore, it is evident that this work will play a significant role in the system design including analysis of the distribution of products and ash deposit in the downdraft gasifiers

Efficient Online Timed Pattern Matching by Automata-Based Skipping

The timed pattern matching problem is an actively studied topic because of its relevance in monitoring of real-time systems. There one is given a log $w$ and a specification $\mathcal{A}$ (given by a timed word and a timed automaton in this paper), and one wishes to return the set of intervals for which the log $w$, when restricted to the interval, satisfies the specification $\mathcal{A}$. In our previous work we presented an efficient timed pattern matching algorithm: it adopts a skipping mechanism inspired by the classic Boyer--Moore (BM) string matching algorithm. In this work we tackle the problem of online timed pattern matching, towards embedded applications where it is vital to process a vast amount of incoming data in a timely manner. Specifically, we start with the Franek-Jennings-Smyth (FJS) string matching algorithm---a recent variant of the BM algorithm---and extend it to timed pattern matching. Our experiments indicate the efficiency of our FJS-type algorithm in online and offline timed pattern matching

Effect of Process Parameters on the Surface Roughness and Kerf Width of Mild Steel during Plasma Arc Cutting Using Response Surface Methodology

This study investigated the effects of process parameters of plasma arc cutting (PAC) of low carbon steel material using analysis of variance. Three process parameters, cutting speed, cutting current and gas pressure were considered and experiments were conducted based on response surface methodology (RSM) via the box-Behnken approach. Process responses viz. surface roughness (Ra) and kerf width of cut surface were measured for each experimental run. Analysis of Variance (ANOVA) was performed to get the contribution of process parameters on responses. Cutting current has the most significant effect of 33.43% on the surface roughness and gas pressure has the most significant effect on  kerf width of  41.99% . For minimum surface roughness and minimum kerf width, process parameters were optimized using the RSM. Keywords: Cutting speed, cutting current, gas pressure,   surface roughness, kerf widt

Time Finite Element Chatter Stability Characterization of a Three Tooth Plastic End-Milling Cnc Machine

Abstract People working in workshop have observed that there exist magic spindle speeds for any milling tool-workpiece co mbination at which optimal depth of cuts are allowed. So me of them have tried to unravel these magic spindle speeds experimentally. This is a very time consuming, costly and inaccurate optimization procedure thus the purpose of this work is to outline an analytical solution to not only the problem of finding the magic spindle speeds but also problem of separating the whole of stable operations from the unstable ones. Slotting three tooth end miller was studied using the method of time fin ite element analysis (TFEA) and validated using the result of time do main stability analysis stemming fro m MATLAB dde23 solution of the milling equation. It is seen for the studied system that though accuracy improves with increase in number of t ime elements used, only marginal gain in accuracy could be achieved by increase in number of elements above ten finite time elements. In other words close agreement exists between the two approaches (TFEA and MATLAB dde23) when the number of time elements is high enough. Fourteen time elements were used to generate a working chart for the studied system. The stability chart is seen to exh ibit milling stability characteristics of magic spindle speeds already known by workshop practitioners. The major imp licat ion of this study becomes that time loss that is occasioned by experimental trial and erro r method of determin ing the productive spindle speeds is avoided